Mineral spirits (paint thinner) and naphtha dilute and clean up oils and varnishes, including oil-based polyurethane varnish. Neither of these solvents damage any fully dried finish, so you can safely use them for cleaning—that is, removing grease or wax.Denatured alcohol thins and cleans up shellac. This solvent will damage a dried shellac finish almost instantly and lacquer and water-based finish fairly quickly, so be very careful if you use alcohol for cleaning.
Lacquer thinner and acetone thin and clean up all solvent-based lacquer products. These solvents can damage all wood finishes, so don’t use them for cleaning.
